The present invention relates to a method of manufacturing paper, cardboard, or another equivalent fiber web having the property of being stretchable and/or the property of having a high coefficient of friction, wherein the paper web has been shortened or upset in a known way and is then conveyed, while interposed between a pair of felts, or between a felt and a wire, or between two wires, through a first press nip and thereafter while adhering to one of the felts at all times to at least one additional press nip where the web is also interposed between a pair of felts or between two wires or between a wire and a felt.
The Finnish Pat. No. 44,334 relates to a method according to which paper having a good friction characteristic and/or a certain stretchability is manufactured. According to this known method the paper is initially subjected to deformation in such a way that the length of the paper is shortened to a given extent. Thereafter the paper web which has thus been shortened by way of a type of upsetting process is conveyed substantially unchanged between two felts or wires into the press section. Subsequent to the first press nip of the press section the web adheres to one of the felts or wires and is then conveyed thereby together with this felt or wire to a second press nip. According to this patent the second above-mentioned wire or felt also may be conducted to the second press nip, and of course there may be several such press nips.
It has been found that the achievement of a relatively high elongation capability in a paper web implies that the dry matter content thereof can be made high enough at the stage where the paper web is detached from contact with the felt or wire which conveys the same. It is therefore important that the dewatering be as high as possible at each press nip.